A singer riding the wave of her peak. There's nothing special about "Roar," it's a generic (and contrary to what some people rationalize around here, generic isn't good or acceptable) fluff piece that won't age gracefully or last the test of times.
But...Katy is where Gaga was when "Born This Way" was released. She's coming off of a hit album and a bunch of previous hit songs, and therefore has built up enough credit to be automatically embraced with a new song, no matter how subpar it is.
"Applause" is an overproduced, try-hard attempt at recapturing the glory of a singer whose credit ran out with her last album. The music listening public trusts Katy, that's why "Roar" is a hit. They don't trust Gaga as much, which is why "Applause" is struggling.
But this kind if credit won't last. Katy is where Gaga was with BTW. An out of the gate hit on nothing but her name, but again that kind of credit won't last indefinitely. Like Gaga last time, Katy's new album most likely won't do what the last one did, and the album after it will see her struggling like Gaga is now.
Listeners being able to relate to songs doesn't always mean they'll be successful, and songs that aren't relatable are not always unsuccessful. I think that's a lazy argument. Look at Viva La Vida
Also, Applause is extremely generic, moreso than Roar. Have you heard the instrumental?
